Taxus wallichiana

Zucc.

Taxaceae

In most of the literature before the year 2000 only the species Taxus wallichiana Pilg., is recognized as native to the Himalayan mountain chain [often referred to as Taxus baccata ssp. wallichiana (Zucc.) Pilg.]. More recently, all of the populations occurring from central Nepal westward to northern Pakistan and Afghanistan have been assigned to the species Taxus contorta Griff. It is quite distinct from both Taxus wallichiana and from Taxus baccata, which does not reach further east than Northern Iran[

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] but these are now treated as distinct species. In Malesia, the species Taxus celebica and Taxus sumatrana, although sometimes considered to be distinct, do not differ consistently in their morphological characters from Taxus wallichiana and are included here as synonyms[

A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.

].
The species of Taxus are more geographically than morphologically separable; and they were all treated by Pilger (1903) as subspecies of Taxus baccata. All species are poisonous; most contain the anti-cancer agent taxol; and a study of heartwood constituents of Taxus baccata, Taxus brevifolia, Taxus cuspidata and Taxus floridana found them to be chemically almost identical. However, the vast ecological amplitude displayed by the various described species (over 60Â° of latitude and an impressive temperature and precipitation range) suggests that they are, in a meaningful sense, true species. Detailed study of the genus (not neglecting the cultivated representatives), including extensive fieldwork, is much needed and long overdue[

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General Information

Taxus wallichiana is an evergreen shrub or a tree. In open situations on rocky slopes and cliffs it usually forms a large, broadly spreading shrub, but in woodland it is more likely to become a small to medium-sized tree[

A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.

].
The plant is harvested from the wild for local use as a food, medicine and source of materials. The leaves and bark have been harvested commercially from the wild as a source of the anticancer drug taxol'. This harvesting has proved to be unsustainable, and efforts are being made to cultivate the plant for this purpose. It is sometimes grown as an ornamental, mainly in Asia[

A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.

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Across most of its range through the Himalayas and western China, Taxus wallichiana has been heavily exploited for its leaves and bark which are used to produce the anti-cancer drug paclitaxel or similar chemicals. Declines of up to 90% have been reported in India and Nepal while in western China declines of more than 50% have been reported. The degree of exploitation in Myanmar is uncertain. In Viet Nam the subpopulation is limited to several hundred trees within a very limited area of Lam Dong Province. This remnant subpopulation was more extensive in the recent past but has declined due to deforestation and conversion of forests for agriculture. The status of Taxus populations in the Philippines and Indonesia is less clear. Some reports of exploitation associated with taxol production have come from the Philippines (Agillion 2007) but these have not been well documented. Although the Philippines has lost the vast majority of its forest cover through logging and agricultural expansion, the degree to which this has effected Taxus is unknown and ground truthing of both recent and historic records is needed. In Sulawesi and Sumatera widespread deforestation has been concentrated in the lowlands rather than the montane areas where estimates of decline are as low as 5% (Cannon et al. 2007, Laumonier et al. 2010). As with the Philippines further field work is required to ascertain the status of Taxus in these areas. The plant is classified as 'Endangered' in the IUCN Red List of Threatened Species(2013)[

A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.

].

Known Hazards

All parts of the plant, except the flesh of the fruit (actually an aril), are potentially highly poisonous. They contain the alkaloid taxine and , if ingested, can cause nervousness, trembling, slow pulse, pupil dilation, difficult breathing, abdominal pain, vomiting, diarrhoea, weakness and convulsions - in larger doses it can be fatal, having a paralyzing affect on the heart[

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].

Botanical References

Range

Habitat

A small to large understorey or lower canopy tree in montane, temperate, warm temperate, and tropical submontane to high montane coniferous, broad-leaved and mixed forest; at elevations from 900 - 3,700 metres[

Basic cultivation details, plant uses, habitat etc for several thousand species of plants, mainly from the temperate zone.

].
Since the exploitation of Himalayan yew for its foliage containing taxanes has proved to be unsustainable, cultivation efforts are being undertaken in the Himalayan foothills and elsewhere in India; this involves both species Taxus contorta and Taxus wallichiana.
Because of its similarity with the European Yew (Taxus baccata), this species is rarely found in cultivation in Europe, but is used as an ornamental elsewhere, as in Baguio, Philippines[

Notes from observations, tasting etc at Plants For A Future and on field trips.

]
All other parts of this plant, including the seed, are highly poisonous. When eating the fruit you should spit out the large seed found in the fruit's centre. Should you swallow the whole seed it will just pass straight through you without harm. If it is bitten into, however, you will notice a very bitter flavour and the seed should immediately be spat out or it could cause some problems. The fruit is a fleshy berry about 10mm in diameter and containing a single seed[

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Medicinal

The alkaloid compounds (taxanes) of the bark are a source for the anti-cancer drug paclitaxel (Taxol) which has become a major reason for exploitation in recent years. The leaves yield similar chemicals in low concentrations[

A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.

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The following uses were originally stated for Taxus baccata growing wild in India. It is now considered that Taxus baccata is not found wild in India and that references to that taxon apply to Taxus mairei and Taxus wallichiana (both in the eastern Himalayas) and Taxus contorta (in the western Himalayas)
The leaves and fruits are antispasmodic, aphrodisiac, emmenagogue and sedative[

A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.

].

The wood is durable and strong. It is used for door frames, cabinet work and wood turning and wood inlaying, also for candlesticks, knife handles etc. Less refined products are gates and fences, poles, struts and 'wattle and daub' in walls of rural buildings[

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]. It is best sown as soon as it is ripe in the autumn when it should germinate 18 months later. Stored seed may take 2 years or more to germinate. 4 months warm followed by 4 months cold stratification may help reduce the germination time[

]. Harvesting the seed 'green' (when fully developed but before it has dried on the plant) and then sowing it immediately has not been found to reduce the germination time because the inhibiting factors develop too early[

Does not deal with many species but it is very comprehensive on those that it does cover. Not for casual reading.

]. Prick out the seedlings into individual pots once they are large enough to handle and grow them on in pots in a cold frame. The seedlings are very slow-growing and will probably require at least 2 years of pot cultivation before being large enough to plant out. Any planting out is best done in late spring or early summer, after the last expected frosts[